Rotary motion devices are commonplace articles in various industries and in everyday life. One example of a rotary motion device is a rotary motor. A rotary motor converts from an input energy (e.g., electrical energy applied to a coil) to mechanical energy. Typically, the mechanical energy is output as rotary motion of a shaft.
Rotary motion devices are not limited to motors. Indeed, rotary motion may be defined simply as motion in a circle. Thus, well known rotary motion devices may also include, for example, devices that convert: rotary motion to linear motion, such as via wheels or a rack and pinion; rotary motion to reciprocating motion, such as via a piston, a geared mechanism, or a Cardan gear; rotary motion to oscillation, such as via a crank or quick return; rotary motion to intermittent motion, such as via a Geneva stop; and rotary motion to irregular motion, such as via a cam. Rotary motion devices are also commonplace in several other applications, including, for example, medical, space, robotic, and biomimetic applications, micro-electro-mechanical systems (MEMS), entertainment devices, and devices requiring vibration sensing.
Traditional rotary motion devices are often heavy, bulky, and unsuitable for many applications, such as those requiring light weight, continuous output, or both. More recent advances address certain of these drawbacks, and include the use of electroactive polymers (“EAP”s). EAPs convert between input energy and mechanical energy. In the context of a rotary motor, a voltage is applied to electrodes contacting an EAP, causing the EAP to deflect. This deflection is converted into rotary motion, namely, rotation of a power output shaft. Repeated deflection of the polymer may produce continuous rotation of the power shaft.
Known uses of EAPs for rotary motion devices have been primarily limited to linear deflection of EAPs and/or a device construction that must overcome both the resistance of the article upon which work is being performed (e.g., the turning resistance of a motor shaft) and the force of gravity (e.g., pulling the weight of a motor crank arm against gravity).
The present embodiments disclose the use of EAPs in rotary motion devices that may overcome one or more of the limitations of traditional rotary motion devices and known EAP-based rotary motion devices.